Now that the federal government has decided to sue him for fraud, Lance Armstrong plans to argue that the case against him is too old to pursue and that he never submitted a false claim to the government, according to a person close to Armstrongs defense team.

The person, who spoke on condition of anonymity because of the sensitivity of the matter, also told USA Today Sports on Monday that Armstrongs legal team will argue that the government knew or should have known about doping on the U.S. Postal Service cycling team  but did nothing to stop it.

We will say there was enough information (about doping on the USPS team) to put you (the government) on notice, and you should have filed a false claim before, the person in Armstrongs camp says.

The strategy shows the tightrope of technicalities that Armstrong will seek to walk after the U.S. Justice Department announced Friday that it has joined a civil fraud case against Armstrong under the False Claims Act.

Armstrong vigorously denied doping for more than a decade before finally confessing last month on national television. But the governments case against him will not be about whether he cheated. Instead, it is likely to come down to legal issues such as the six-year statute of limitations and the legal definition of a false claim.

Another key question likely to be argued early: What did the USPS know and when did it know it?

The law is that if the government knew of the fraud, you cant prosecute someone for fraud, said Tony Anikeeff, an attorney who specializes in similar cases for the firm Williams Mullen. (The governments argument) will be that he denied it vociferously for years and kept them in the dark.

Anikeeff, who is not involved in the case, said a big early hurdle for the government will be the statute of limitations.

The lawsuit was first filed in 2010 by another confessed cycling cheat, Floyd Landis, Armstrongs former USPS teammate. It argues that Armstrong and his associates defrauded the government through their doping scheme on the USPS team. Because Armstrong and others used banned drugs and blood transfusions to boost themselves on the bike, the lawsuit argues they violated their USPS sponsorship contracts and that the government should get its money back.

USPS paid $31 million to sponsor Armstrongs team from 2001 to 2004. Under the False Claims Act, Landis can seek to recover triple that amount for the government  possibly more than $90 million, with Landis getting at least 25 percent as the whistleblower who brought the case to the governments attention.

Armstrongs attorneys will argue that the whole case should be thrown out because of the six-year statute of limitations, which started when Landis filed the case in 2010. At best, they will say the six-year statute bars all but one year of the USPS sponsorship from the lawsuit  2004. In response, Anikeeff said the government is expected to argue that the fraud was concealed and that the six-year rule shouldnt apply.

Thats why Armstrongs legal team will argue the USPS knew or should have known about the doping issues long ago.

The person close to Armstrongs defense said that as doping allegations swirled around the USPS team, the USPS didnt investigate or file for a false claim but instead offered to hire a public-relations firm to boost its image.

If proven, this could hurt the governments case.

Another issue the person said Armstrongs team will argue is the definition of a false claim itself. The person said Armstrong never entered into a contract with the USPS or the government, so he could not have submitted a false claim to them. The USPS contracts instead were with Tailwind Sports, the management company of Armstrongs cycling team. Tailwind also never certified that its riders wouldnt or didnt dope, the person said.